Stitch-foot for use in double-needle sewing machines for the manufacture of helical-wire slide fasteners



Oct. 28, 1958 H. POREPP 7,

STITCH-FOOT FOR USE IN DOUBLE-NEEDLE SEWING MACHINES FOR THE MANUFACTUREOF HELICAL-WIRE SLIDE FASTENERS Filed Feb. 19, 1957 2 Sheets-Sheet 1F/G'. a

Oct. 28, 1958 H. POREPP 2,857,866

STITCH-FOOT FOR USE IN DOUBLE-NEEDLE SEWING MACHINES FOR THE MANUFACTUREOF HELICAL-WIRE SLIDE FASTENERS Filed Feb. 19, 1957 2 Sheets-Sheet 2 ,gm l vylllllll-lrlllrlllf/l #vravrae; M/VS FOX/"ff United States Patent2,857,866 Patented Oct. 28, 1.958

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STITCH-FOOT FOR USE IN DOUBLE-NEEDLE SEWING MACHINES FOR THE MANUFAC-TURE F HELICAL-WERE SLIDE FASTENERS Hans Porepp, Essen, Germany,assignor to tlpti Wei-h G. m. b. H., Essen, Germany This inventionrelates to the manufacture of helicalwire slide fasteners consisting oftwo helical wires of metal or plastic material and of opposite twistwhich through suitable profiling or the like engage or disengage eachother.

For the attachment of these helical wires to two attachment tapes oftextile or artificial material the invention proceeds as follows: Thehelical wires are provided on the sides thereof located opposite thesides on which they engage each other with a longitudinally extendingthread resting against the turns and are secured to the wires by afastening thread between every turn of the Wires. These longitudinallyextending threads and fastening threads are then, together with a guidecord covering up the threads sewed to the attachment tapes. For thispurpose the two helical wires provided with the fastening threads arebrought into engagement with each other, whereupon the longitudinallyextending threads and their fastening threads as well as the guide cordsare sewn to the two attachment tapes by means of double-needle sewingmachines. It is understood that the customary sewing machines of thistype can be used for this purpose only with greatest difiiculty andunsatisfactory results, as it is necessary to arrange the two attachmenttapes, the two interlocked helical wires provided with thelongitudinally extending threads and the fastening threads therefor, aswell as the two guide cordsthat is to say, five semi-finished productsof rather different propertiesaccurately on top of each other (on eachside of the space 1, Figure 1), directly under the needles, in order toachieve a perfect sewing result.

In order to make sure that the different parts of the helical-wire slidefasteners can be relied upon to register correctly and then can be sewedup together accordingly, without making it necessary for the woman doingthe needlework or for an assistant of the latter to pass the individualparts onto the machine, or to an attachment for the purpose, theinvention proposes to employ for the manufacture of helical-wire slidefasteners of the aforesaid kind a novel type attachment, herein called astitch-foot, for a double-needle sewing machine. The invention isprincipally characterized by the feature: that the stitch-foot consistsof a lower plate and an upper plate and is provided on the feed-in sidebetween the two plates with a guide member along which the twoattachment tapes slide in flatly crossed position with the two inneredges confronting each other, whereupon the two attachment tapes areadjusted to straight-lined and parallel position in a guide chamberlocated between the two plates and corresponding in thickness and widthto the dimensions of the completed slide fastener; that the lower plateis provided behind the place where the two attachment tapes cross eachother with two bores for the passage of the needles; that the upperplate is provided with a slot extending from the forward edge of theplate to the passage for the needles and corresponding in 7 width to thewidth of the two interlocked and longitudinally moving helicalwires;that in the area ofthe More said slot before the needles twolongitudinally extending guides are located for the guiding of the twoguide cords covering up the longitudinally extending threads andfastening threads of the helical wires; and thatfro-m the passage forthe needles a groove extends along the: underside of the upper plate tothe rear end of the latter whose width and height corresponds to. thewidth and. height of the two helical wires provided with the. sewed onguide cords.

' By means of this novel. type of stitch-foot it is possible to sewthese different semi-finished products, whose dimensions vary withinslight permissible limits, in accurately guided condition, speedilytogether to form.helicalwire slide fasteners. It is important that thetwo attachment tapes be fed to the stitch-foot in flatly crossedposition, as it is possible only in this Way to maintain the two inneredges of the tapes, independent of slight variations in width,constantly in uniformly tensioned condition and at a uniform distancefrom each other, sothat they assume in the stitch-foot particularlybefore the needles-correct positions with respect to each other. The useof guiding means for the edges of the tapes for the straight-lined andparallel feeding of the two tapes into the stitch-foot doe not producesatisfactory results, as has been found out through numerous tests. Thereason for this is that there are always slight variations in width, ofthese textile bands, which variations may result in variations of the.position of the bands with respect to each other in the area of the twoneedles, and in the manufacture of arched or crooked slide fasteners.

Additional features and advantage of the invention will be understoodfrom the following detailed description taken in connection with theaccompanying drawings forming a part of this specification and in whichan embodiment of the principle of the sewing action for the manufactureof helical-wire slide fasteners, and also an embodiment of thestitch-foot of the invention have been shown by way of example. However,Iwish to say that the invention is not confined to any strict conformitywith the showing of the drawings but may be changed or modified, so longas such changes or modifications mark no material departure from thesalient features ofthe invention as expressedin the appending claims;

In the drawings, in whichlike parts are referred to by the samereference numerals,

Fig. 1 is a top planview of the attachment tapes; of the interlockedhelical wires provided'with longitudinally extending threads andfastening threads; andof the guide cords guided in the stitch-foot;

Fig. 2 is a side elevation of Fig. 1;

Fig. 3 is a cross-section on line Ill-IIl"of"Figs. 1 and'2;

Fig. 4 is a side elevation of the stitch-foot of themvention';

Fig. 5 is (left hand side) a front viewof'the feed'side of thestitch-foot; and (right hand side) a cross-section directly before thetwo needles;

Fig. 6 is a top plan view of'the stitch-foot. At the lower half of thefigure the upper plate of the stitch-foot has been removed.

Fig. 7 is a top plan view of the lower plate of the stitch-foot;

Fig. 8 is a side view of the lower plate of Fig; 7;

Fig. 9a is a top plan view of the cross-guide for thetwo attachmenttapes;

Fig. 9b'is a front view of the cross-guide for the two: attachmenttapes;

Fig. 10 is a top plan view of the upper plate offthe stitch-foot;

Fig. 10a is a central longitudinal section through the: upper plate ofFig. 10;

Fig. 10a isa frontview of the upper plate;

Fig. 11a is atop plan view of acordguide;

Fig. 11b is a side view of a cord guide.

The helical-wire slide fasteners consist of two helical Wires ofopposite twist A A which through suitable profiling or by some othermeans tightly interlock; of two attachment tapes B B and of two guidecords C and C The guide cords serve the purpose of guiding the twohelical wires, of metal or plastic material, in a slider for producingthe interlocking engagement or for severing it. For securing these partsto each other by stitching, the two helical wires A A are provided alongtheir outsides with longitudinally extending threads A A which aresecured to the helical wires by means of fastening threads. Then thehelical wires are placed upon the tapes B B along the inner edges of thelatter; thereupon the longitudinally extending threads A A are coveredup by the guide cords C C and then the cords and the longitudinalthreads and fastening threads of the latter are sewed to the two tapes.For this a doubleneedle sewing machine is employed; and for obtaining acorrect covering up the invention uses a stitch-foot hereinafterdescribed to which the two attachment tapes B and B are fed as shown inFig. 1, that is to say, flatly crossing each other. Provided in thestitch-foot is a guide member, for example an elongated rib F, whosewidth corresponds to the distance 1 between the two inner edges of thetwo tapes of the completed slide fastener. The height of the rib Fcorresponds to the thickness of the two tapes B B Directly in front ofthe two sewing needles D D the interlocked helical wires A A are fed tothe two tapes B B longitudinally towards the needles, over the tapes.Furthermore, there are fed, likewise longitudinally towards the needles,over the tapes, the two guide cords C C in such fashion that they coverup the longitudinal threads A A and fastening threads a. Thereafterthese parts are sewed together.

In order to be able to carry out the aforedescribed method of sewing theparts A B C and A B C together with accurate precision and great speed,the invention employs the stitch-foot as hereinafter described. Thisstitch-foot consists essentially of a lower plate 1 and an upper plate2, which are provided with a stitchfoot handle 3. The lower plate is ofrectangular shape and laterally terminates in two longitudinallyextending upwardly projecting ribs 5 and 6. These two ribs 5 and 6 have,compared with the rear surface portion 1a of the plate, a heightcorresponding to the thickness of the tapes B B and their distance fromeach other corresponds to the entire width of the completed slidefastener. The forward portion 1b of the plate surface is, compared withthe height of the ribs 5 and 6, of larger depth than the rear surfaceportion 1a, whereby this depth corresponds to at least double thethickness of the tapes B B Behind the step between the surface portions1b and 112 there are two bores 7 through which the sewing needles D Doperate. Ahead of the bores 7, in the area of the forward surfaceportion 1b, there is arranged the guide member for the crosswise feedingof the two attachment tapes B B According to Figs. 9a and 91), thisguide member consists of a thin plates whose entire thicknesscorresponds to the depth of the forward surface portion 1b of the lowerplate 1 as compared with the ribs 5 and 6 of this plate. The width ofthis plate 8 is smaller than the distance of the ribs 5 and 6 from eachother, so that this plate after its arrangement in the recess 1b of thelower plate 1 can be shifted in a transverse direction. For this purposethe plate is provided with laterally projecting portions 8a and 81)extending through recesses 9 of the lower plate 1, so that in this way aguide is provided for the plate 8 as shown in Fig. 7 in broken lines.For the adjustment of the plate 8 the projecting portion 8a of the plateis provided at its free end with a downwardly bent flanged end portion80,

. and this downwardly bent end portion 80 is provided with a threadedbore for the engagement therein of a setscrew 8d. In addition to this,the projecting portions guide cords C C 8a and 8b are provided withtransversely extending elongated slots 10 and 11 by means of which theguide plate 8 can be screwed to the lower plate 1 of the stitch-foot inthe required adjusted position.

The plate 8 is provided in its under surface and upper surface withseats 12 and 13, of which one is positioned on one side and the otherone on the other side of the longitudinal center line of the plate. Theinner delimitation shoulders 14 and 15 of these seats, whose depthcorresponds to the thickness of the attachment tapes B B extend from theforward end to the rear end of the plate in oppositely inclineddirections toward the longitudinal center line of the plate andintersect the longitudinal center line shortly ahead of the rear edge ofthe guide plate 8 in such manner that the rear ends of the two shouldersTM and 15 are positioned in a transverse direction at a. slight distancefrom each other, which distance corresponds to the distance from eachother of the two inner edges of the two attachment tapes B B of thecompleted slide fastener. It is understood that the guide plate 8 is soadjusted in the lower plate 1 of the stitchfoot that the longitudinalcenter lines of this guide plate and of the lower plate registervertically. Placed upon this lower plate 1 is then the upper plate 2 (ofwidth equal to that of the lower plate 1) which is secured to the plate1 by means of bolts extending through the bores 16 of plate 1 andcorrespondingly threaded bores 17 of plate 2. Because of the flatundersurface of the upper plate 2 there is defined between the plates 1and 2 in the surface area 1a of the lower plate 1 a rearwardly extendingguide chamber having the width of the completed slide fastener and aheight corresponding to the thickness of the attachment tapes B B Thedistance between the forward edge and rear edge of the guide plate 8 issmaller than the distance between the forward edge of the lower plate 1and the step-edge 10, so that between the rear edge 82 and the step-edge1c a deep recess exists corresponding to the entire thickness of theplate 8. This makes it possible for the tapes B B which cross each otherin flat position, and which pass through the recesses 12 and 13 of theguide plate 8, to adjust themselves horizontally before entering thespace between the surface portion 1a and the undersurface of the upperplate 2.

The upper plate 2 (Figs. 10, 10a) is provided with a slot 19 extendingfrom its forward edge as far as the passage 18 for the two needles,which passage 18 registers with the two bores 7 of the lower plate, andthis slot 19 is of a width corresponding to the width of theinterlocking helical wires A A and of the guide cords C C Behind thepassage 18 for the needles the upper plate is provided on its undersidewith a longitudinally extending groove 20 whose width and depthcorrespond to the width and depth of the joined helical wires A A andthe sewed on guide cords C C To the slot 19 the two interlocked helicalwires A A are fed in the longitudinal direction of the slot 19, and fromabove the two guide cords C C are fed in such manner that these guidecords correctly register with, that is to say, are correctly positionedon top of the longitudinally extending threads A A and fastening threadsof the helical wires. For this purpose the upper plate 2 is provided,ahead of the passage 18 for the needles, and on each side of the slot19, with a transverse groove 21 and 22, respectively. Arranged in thesegrooves are guides 23 (see Figs. 11a, which, by means of slots 24 andappropriate screws, can be adjustably rigidly secured to the upper plate2. These guides 23 have their meeting ends positioned in the area of theslot 19 of the upper plate 2 of the stitch-foot, so that theundersurfaces of these ends prevent the interlocked helical wires fedinto the stitch-foot from deviating in a upward direction. These ends ofthe guides 23 are provided on their upper side with grooves 25 extendingin the longitudinal direction of the stitch-foot and which correspond incross-section to the cross-section of the These guides 23 are soadjusted and fixed in the grooves 21 and 22 that the grooves 25 arepositioned accurately above the longitudinally extending threads A A andfastening threads of the fed-in interlocked helical wires. In order toensure this accurate adjustment each of the guides 23 is provided in oneof its lateral edges with a recess 26 in which is engageable thedisk-like head 27 (Fig. 4) of a nut adapted to be screwed onto athreaded bolt 28. But it is of course also possible to employ a threadedbolt provided with a similar disk, which bolt may then be screwed into aparallel bore of the upper plate 2.

The mode of operation of the stitch-foot is as follows:

First the two attachment tapes B B are pulled in flatly crossed positionthrough the recesses 12 and 13, and thereupon in straightened-outpositions through the flat space between the upper and lows plates 2 andin the area of the upper surface portion 1a of the lower plate 1. Thenthe two interlocked helical Wires A A are passed from the forward endthrough the slot 19, and through the groove 2t? on the underside of theupper plate 2. And then the two guide cords C C are fed from abovethrough the guide grooves 25 and likewise passed slightly deflectedthrough the grooves on the underside of the upper plate 2. Now thesewing of these parts by means of the needles can start, whereby theelements A B C and A B C are in correct positions with respect to eachother or above each other, so that the accurate sewing up of these partscan be carried out with great speed.

What I claim as new and desire'to secure by Letters Patent of the UnitedStates is:

1. A guide device for use in double-needle sewing machines for themanufacture of helical-wire slide fasteners of the type comprising twointerlocked helical wires provided along their opposite outer surfaceswith longitudinally extending fastening threads, respective flexiblefastening tapes for the wires and guide cords covering the fasteningthreads, said guide device comprising a lower plate and a plate rigidlysecured on the lower plate, said plates being recessed at their meetingsurfaces to form a relatively wide horizontal conduit passage having adownwardly facing longitudinal groove at the center of its rear portion,said passage being of a height, at the sides of its rear portion,substantially the same as the thickness of the fastening tapes, and atthe center of its rear portion, substantially the same as the combinedthickness of the tapes and the guide cords, the passage beingsubstantially greater in height at its forward portion than at its rearportion, whereby the tapes, wires and cords may be fed in angularlyseparated relationship into said for ward portion, a guide memberadjustably mounted in said forward portion, said guide member beingformed with crossed guide channels parallel to the plates shaped toslidably receive the respective tapes and guide said tapes in flatlycrossed positions, the inner side edges of said channels being spacedapart at their rear ends by a distance less than the width of the grooveat the center of the rear portion of said conduit passage, said lowerplate being formed rearwardly adjacent said rear ends with two spacedtransversely aligned perforations for the passage of the double needlesof a sewing machine, said upper plate being formed with a longitudinalslot aligned with the groove at the center of the rear portion of saidconduit passage and extending from the forward edge of said upper plate,said slot having a laterally enlarged portion located above saidperforations, the width of said slot being otherwise substantially thesame as the width of the groove at the center of the rear portion ofsaid conduit passage and being substantially the same as the combinedwidth of the guide cords and the interlocked wires, and further guidemeans secured on the upper plate over the slot forwardly adjacent saidperforations and being formed with upwardly facing longitudinal channelssubstantially longitudinally aligned with the respective perforationsfor slidably receiving the guide cords.

2. The structure of claim 1, and wherein the bottom surface of the upperplate is substantially flat at its side portions, and wherein said lowerplate is formed at its side margins with upwardly projectinglongitudinal ribs which at the rear portion of the bottom plate aresubstantially the same in height as the thickness of the tapes and whichat the forward portion of said bottom plate are at least of a heightequal to double the thickness of the tapes, said ribs being spaced apartby a distance substantially equal to the combined widths of the tapesand the interlocked wires.

3. The structure of claim 1, and wherein said guide member comprises atransversely adjustable guide plate and wherein said crossed guidechannels comprise groovelike vertically oflset recesses extending fromthe forward edge to the rear edge of said last-named plate, the inneredges of said last named recesses being oppositely inclined and crossingeach other a short distance forwardly of the rear edge of the guideplate.

4. The structure of claim 3, and wherein the groovelike recesses aresubstantially symmetrically located on opposite sides of thelongitudinal center line of the guide plate and wherein said inner edgesof the groove-like recesses converge rearwardly from the forward edge ofthe guide plate.

5. The structure of claim 3, wherein the rear edge of the guide plate isspaced forwardly a substantial distance from the forward edge of therear portion of said conduit passage.

6. The structure of claim 1, and wherein said upper plate is formed withtransverse grooves located forwardly of said perforations, and whereinsaid further guide means comprises transverse bar members adjustablymounted in said last-named grooves and formed with said upwardly facinglongitudinal channels.

References Cited in the file of this patent UNITED STATES PATENTS2,274,721 Marinsky et a1 Mar. 3, 1942 2,329,991 Kellum. Sept. 21, 1943

